趋向指标DMI 计算及详解

为上升指标和下降指标的总和

adx

就是

dx

的一 定周期

n

的移动平均值。

5

）计算评估数值

ad xr

在

dmi

指标中还可以添加

adxr

指标，以便更有利于行情的研判。

adxr

的计算公式为：

（当日的

adx

＋前一日的

adx

）÷

2

和其他指标的计算一样，由于选用的计算周期的不同，

dmi

dmi

指标、

周

dmi

指标、月

dmi

dmi

指标以及分钟

dmi

指标等各种类型。经常被用于股市研

判的是日

dmi

指标和周

dmi

指标。虽然它们的计算时的取值有所不同，但基本的计算方法

一样。另外，随着股市软件 分析技术的发展，

投资

者只需掌握

dm i

形成的基本原理和计算

方法，无须去计算指标的数值，更为重 要的是利用

dmi

指标去分析、研判股票行情。

Directional Movement Index (DMI)

Description

The

Directional

Movement

Index

(also

known

as

DMI)

is

a

momentum

indicator

that

was

developed

by

J.

Welles

Wilder.

It

is

calculated

using

the

price,

compares the current price with the previous price range, and displays

the

result

as

an

upward

movement

line

(+DI),

and

a

downward

movement

line

(-DI), between 0 and 100. The DMI also calculates the strength of the

upward

or

downward

movement,

and

displays

the

result

as

a

trend

strength

line (ADX).

The DMI is displayed on its own chart, separate from the price bars, and

is the lower section in the chart shown above.

Calculation

?

?

Description:

The DMI is the ratio of exponential moving averages of the greater of the upward (U)

and downward (D) price movements, and the true range (TR).

Calculation:

U = Hn - Hn-1

D = Ln-1 - Ln

TR = (Hn - Ln) | (Hn - Cn-1) | (Cn-1 - Ln)

EMAUP = EMAUn-1 + ((2 / (n + 1)) * (Un - EMAUn-1))

EMADOWN = EMADn-1 + ((2 / (n + 1)) * (Dn - EMADn-1))

EMATR = EMATRn-1 + ((2 / (n + 1)) * (TRn - EMATRn-1))

+DI = EMAUP / EMATR

-DI = EMADOWN / EMATR

DX = ABS(+DI - -DI) / (+DI + -DI)

ADX = EMADXn-1 + ((2 / (n + 1)) * (DXn - EMADXn-1))

Trading Use

The Directional Movement Index can be used in

both

ranging

and

trending

markets.

In

general,

when

the

+DI

line

is

above the -DI line, the market is moving upwards, and when the -DI line

is

above

the

+DI

line,

the

market

is

moving

downwards.

The

ADX

line

shows

the

strength

of

the

move,

and

the

market

is

considered

to

be

trending

when

the

ADX

line

is

above

30,

and

ranging

when

the

ADX

line

is

below

30.

There

are several trading systems that use the DMI, so there are several

alternative uses of both the DI lines, and the ADX line.

（

ranging and trending markets

Definition:

Day trading markets are referred to as either ranging or trending depending upon the

type of price movement that is currently occurring. The descriptions of these types of

markets are as follows :

Ranging

A ranging market is a market where the price is moving back and forth between a

higher price and a lower price. The higher price would be acting as resistance

because it prevents the price from moving above it, and the lower price would be

acting as support because it prevents the price from moving below it.

The price range of a ranging market can be small or large, and if the range is very

small the market would be considered to be in chop (moving sideways with very little

upward or downward movement).

Trending

A trending market is a market where the price is moving in a single direction, either up

or down, but not sideways.

There may be several small price reversals, but nothing large enough to prevent the

price movement from continuing in its original direction. A day trading trend may last

for a few minutes or a few hours, and longer term trends

may last for several weeks

or months.

）

DMI Points The Way To Profits

By

Candy Schaap

A

A

A

< br> |

The primary objective of the trend trader is to enter a trade in the

direction of the

trend

. Reading directional signals from price alone can

be difficult and is often misleading because price normally swings in both

directions and changes character between periods of low versus high

volatility.

The

directional movement indicator

(also known as the directional

movement index - DMI) is a valuable tool for assessing price direction

and strength. This indicator was created in 1978 by J. Welles Wilder,

who also created the popular

relative strength index

. DMI tells you when

to be long or short. It is especially useful for trend trading strategies

because it differentiates between strong and weak trends, allowing the

trader to enter only the strongest trends. DMI works on all time frames

and can be applied to any underlying vehicle (stocks, mutual

funds,

exchange-traded funds

, futures, commodities and currencies).

Here, we'll cover the DMI indicator in detail and show you what

information it can reveal to help you achieve better profits. (For

background reading, see

Momentum And The Relative Strength Index

.)

DMI Characteristics

DMI is a moving average of range expansion over a given period (default

14). The

positive directional movement indicator

(+DMI) measures how

strongly price moves upward; the

negative directional movement

indicator

(-DMI) measures how strongly price moves downward. The two

lines reflect the respective strength of the bulls versus the bears. Each

DMI is represented by a separate line (Figure 1). First, look to see which

of the two DMI lines is on top. Some short-term traders refer to this as

the

dominant

DMI. The dominant DMI is stronger and more likely to

predict the direction of price. For the buyers and sellers to change

dominance, the lines must cross over.

A

crossover

occurs when the DMI on bottom crosses up through the

dominant DMI on top. Crossovers may seem like an obvious signal to go

long/short, but many short-term traders will wait for other indicators to

confirm the entry or exit signals to increase their chances of making a

profitable trade. Crossovers of the DMI lines are often unreliable

because they frequently give false signals when volatility is low and late

signals when volatility is high. Think of crossovers as the first indication

of a

potential

change in direction. (For more insight, read the

Moving

Averages

tutorial.)

Source: TDAmeritrade Strategy Desk

Figure

1:

The

+DMI

and

-DMI

are

shown

as

separate

lines.

There

are

several false crossovers ( Point 1) and one crossover at Point 2

that

leads

to

an

uptrend

with

+DMI

dominant.

Note:The

calculations

for DMI are complicated and are referenced elsewhere. Also, DMI

is

normally

plotted

in

the

same

window

with

the

ADX

indicator,

which

is not shown.

DMI is used to confirm price action (see Figure 2). The +DMI generally

moves in sync with price, which means that the +DMI rises when price

rises, and it falls when price falls. It is important to note that the -DMI

behaves in the opposite manner and moves counter-directional to price.

The -DMI rises when price falls, and it falls when price rises. This takes a

little getting used to. Just remember that the strength of a price move up

or down is always recorded by a peak in the respective DMI line.

Reading directional signals is easy. When the +DMI is dominant and

rising, price direction is up. When the -DMI is dominant and rising, price

direction is down. But the strength of price must also be considered. DMI

strength ranges from a low of 0 to a high of 100. The higher the DMI

value, the stronger the prices swing. DMI values over 25 mean price is

directionally strong. DMI values under 25 mean price is directionally

weak.

Source: TDAmeritrade Strategy Desk

Figure 2: DMI is weak at Point 1 and price is choppy. The +DMI

rises

strongly

above

25

at

Point

2

and

the

uptrend

follows.

Note

how +DMI moves with price at Point 3 and -DMI moves

counter-directional to price at Point 4.

DMI Momentum

The great feature of DMI is the ability to see buying and selling pressure

at the same time, allowing the dominant force to be determined before

entering a trade. The strength of a

swing high

(bulls) is reflected in the

+DMI peak, and the strength of a

swing low

(bears) is seen in the -DMI

peaks. The relative strength of the DMI peaks tells the momentum of

price and provides timely signals for trading decisions. When the buyers

are stronger than the sellers, the +DMI peaks will be above 25 and the

-DMI peaks will be below 25. This is seen in a strong uptrend. But when

the sellers are stronger than the buyers, the -DMI peaks will be above 25